Certification of Judgment for Registration in Another District (AO 451) is a form used by the United States District Court for the purpose of registering a judgment that was entered in another district within the same state. The form is usually used when a judgment debtor has assets in a different district than the one in which the judgment was entered. This form is used to have the judgment entered the other district, so that the judgment creditor can collect the assets. There are two types of Certification of Judgment for Registration in Another District (AO 451): AO 451A and AO 451B. AO 451A is used to register a judgment from another district within the same state, while AO 451B is used to register a judgment from another district in a different state. Both forms require the information of the parties involved, the date the judgment was entered, and other relevant information.